The invention relates to a method for calibrating measurement signals, which are obtained with optical fibers, and also to a corresponding measurement device. In addition, the invention relates to a method for measuring the temperature in molten masses (melts) by optical fibers, as well as to a measurement device and its use. Here, melts are understood to be both melts of pure metals, such as iron, copper, steel, or alloys, and also cryolite melts, salt melts, or glass melts.
Such devices are known, for example, from German published patent application DE 199 34 299 A1. There, a radiation detector is used for calibrating a measurement system, and a second radiation detector is used for measuring radiation emitted by a radiation source.
The calibration of temperature sensors is known, for example, from British published patent application GB 2 155 238 A and from German published patent application DE 195 32 077 A1. There, a reference material insulated from a thermoelement tip is used for calibration. This is necessary in order to guarantee problem-free functioning of the thermoelement and to prevent its destruction. Such destructive effects are described, for example, in U.S. Pat. No. 3,499,310. There, it is disclosed explicitly that the thermoelement is protected from chemical reactions with the reference material, for example, by a coating.
Other devices are disclosed, for example, in Japanese published patent application JP 63-125906, and in U.S. Pat. Nos. 4,576,486, and 5,364,186.